Potentiale zur energetischen Nutzung von Biomasse in der ... - EPFL

GIS model 191
Bundesamt für Energie BFE
For a more detailed description, it is possible to disaggregate these global volume values into three
classes. Regarding the metadata, a correspondence between tree categories and dbh intervals exists:
Small-size trees = 16–28 cm dbh
Medium-size trees = 28–48 cm dbh
Big-size trees = > 48 cm dbh
Since the proportion of each tree category and the total volume are known, it is therefore possible to
calculate the relative volume for each category of deciduous and coniferous trees.
10.3.4 Estimation of the annual increment of biomass
The assumption is made that the available biomass resource that can be harvested yearly corresponds to
the annual increment in standing trees volume, so that nothing is taken from the actual forest capital.
Thus, the availability factor is a function of the annual growth rate of particular forest types, the surface
they occupied and their volume of biomass.
Annual growth rate
The annual growth rate depends on the vegetation storey in which the forest is located. Storeys
themselves vary with bedrock acidity, geomorphologic nature, aspect and altitude. Bedrock alkalinity
was empirically derived from the geotypes data set using the following classification:
Region Geotype Alkalinity
Plateau
Low slope clay molasse basic
Steepy slope clay molasse basic
Sandstone molasse acid
Conglomerate molasse acid
Jura
Calcareous rocks basic
Limestone-clay alternation basic
Prealps and Alps
Gypsum rocks acid
Clay rocks basic
Calcareous rocks basic
Sandstone shale Flyschs acid
Quaternaire
Alluvial soils varying
Glacial soils varying
Table 53 Alkalinity of geotypes in different regions.
Alcalinity can also be interpreted from the geotechnical map of the Swiss Federal Office of Topography,
including 30 different soil categories.
The geomorphologic conditions that divide the country into supra-regions are available as a GIS layer
from the Swiss Federal Office of Statistics. According to the Swiss National Forests Inventory (FNP/OFEFP
1999) the Jura, the Plateau and the Prealps have the same regional effects on growth rates. Therefore,
no distinction was necessary in our study for the Canton of Vaud, which was considered homogeneous.
The aspect and altitude values are part of the same data set, that is the DHM25. As far as altitudes are
known, it is easy to compute aspects locally within a GIS and classify the values in orientation types as
follows: